KR20100054828A - Catalyst composition and process for converting aliphatic oxygenates to aromatics - Google Patents

Abstract

The invention relates to a catalyst composition La-M/zeolite, which consists essentially of from 0.0001 to 20 mass % of La (lanthanum); from 0.0001 to 20 mass % of at least one element M selected from the group consisting of molybdenum (Mo), cerium (Ce) and caesium (Cs); a zeolite of the 10-ring structure type; and optionally a binder (mass% based on total catalyst composition). The invention also relates to the use of the catalyst composition according to the invention in various reactions, for examples in making aromatics from aliphatic hydrocarbons or oxygenated hydrocarbons with good selectivity and activity. The invention further relates more specifically to a process for converting a feed stream comprising oxygenated lower aliphatic hydrocarbon compounds, especially methanol, to a product stream comprising aromatic hydrocarbons and olefins, especially BTX, which process comprises a step of contacting said feed with the catalyst composition according to the invention.

Description

Catalyst composition and method for converting aliphatic oxygenates to aromatics {CATALYST COMPOSITION AND PROCESS FOR CONVERTING ALIPHATIC OXYGENATES TO AROMATICS}

The present invention relates to a catalyst composition comprising a lanthanum-containing zeolite. The invention also relates to the use of the catalyst composition according to the invention for use in various reactions, such as the preparation of aromatics from oxygenated aliphatic hydrocarbons. The invention also provides a process for converting a feed stream containing an oxygenated lower aliphatic hydrocarbon compound into a product stream containing aromatic hydrocarbons, the feed composition of the catalyst composition according to the invention. And a step of contacting with.

More particularly, the present invention relates to a process and catalyst composition for converting a feed stream containing C1-C4 oxygenates to a product stream containing C6-C8 aromatics.

Such catalyst compositions are known from patent publication US 4156698, wherein a feed containing a C1-C4 monohydric alcohol is modified by a mixture of rare earth metals including crystalline aluminosilicate zeolites such as ZSM-5, and lanthanum (La). It is converted into a mixture of aliphatic and aromatic hydrocarbons by contact with a synthetic catalyst consisting of a modified aluminum matrix. A catalyst composition based on ZSM-5 / alumina and containing 0.26 mass% La is used to convert the methanol feed to hydrocarbons in the gasoline boiling range. Rare earth modifications of the alumina matrix will reduce the decomposition of alcohols to carbon monoxide and hydrogen and increase the conversion to aromatics.

Aromatic hydrocarbon compounds such as benzene, toluene and xylene, often called BTX, are important building blocks in the petrochemical industry today. A common source of these compounds is usually refined petroleum. Because fossil petroleum resources are limited, alternative sources of such aromatics are being developed.

Aliphatic oxygenates that can be obtained from various carbon sources, such as through synthesis gas, can be converted into mixtures containing aromatics such as BTX; Various catalysts for this reaction have already been proposed. For example, US 3894103 describes aromatization of lower oxygenate compounds, such as methanol, by contact with crystalline aluminosilicate zeolites of specific constraint index and Si / Al ratio.

In US 4724270, upon conversion of methanol to hydrocarbons, the selectivity for aromatics is determined when the acidity of the crystalline aluminosilicate zeolites having a specific constraint index and a Si / Al ratio of at least 12 is reduced by heat treatment of this catalyst. It is teaching that it is improved on.

US 4822939 converts Ga-containing ZSM-5 type zeolites having a Si / Al ratio of 5000 to 35000 prior to Ga-exchange to convert C1-C4 aliphatic oxygenates to C2-C5 olefins under improved yield and reduced C1-C5 paraffin formation. Teach you how to use it. At least some of Ga suggests that it must be present in the zeolite framework in tetrahedral coordination to provide Bronsted acid sites, and the zeolite within the framework should be substantially free of aluminum.

WO 03/089135 discloses pentasyl aluminosilicates containing a mixture of rare earth metals including sodium, zinc, and La; This catalyst has been used to prepare mixtures containing liquid hydrocarbons from lower aliphatic hydrocarbon oxygenates. The advantages of this catalyst are indicated by higher yields of high octane hydrocarbons and lower aromatics content.

Vaporised La-modified ZSM-5 / silica / kaolin catalyst compositions are disclosed in WO 99/51549. This catalyst is used to prepare a mixture containing C2-C4 olefins from methanol; Methanol conversion was only 2%.

The La-Cu / ZSM-5 composition is disclosed in US Pat. No. 6,126,912 and is used as a catalyst for reducing NO _x to NO ₂ .

US 5866741 discloses La-Mo / betazeolite compositions which are applied as a catalyst to convert C9 + aromatics to C6-C8 aromatics.

WO 2005/080532 discloses La-Mo-Zn / Y-zeolite compositions, which have been found to be useful as catalysts for converting C6 + hydrocarbons to linear C1-C5 alkanes.

There is a continuing need in the industry for improved performance of catalysts and processes in terms of overall process economics. It is an object of the present invention to provide feed streams containing oxygenated lower aliphatic hydrocarbon compounds with relatively high amounts of aromatic hydrocarbons, in particular BTX. It is to provide a new catalyst composition that can be applied to a method for converting into a product stream containing.

This purpose is 0.0001 to 20% by mass of La (lanthanum); 0.0001 to 20% by mass of at least one M element selected from the group consisting of molybdenum (Mo), cerium (Ce), and cesium (Cs); Zeolites of the 10-ring structure type; It is achieved according to the invention with a catalyst composition La-M / zeolite, consisting essentially of binder (mass% based on total catalyst composition).

The catalyst compositions according to the invention surprisingly exhibit good selectivity with high productivity in converting feed streams containing oxygenated lower aliphatic hydrocarbon compounds into aromatic hydrocarbon containing product streams. The catalyst also has the ability to convert aliphatic or mixtures of methanol and hydrocarbons into aromatics with surprisingly high productivity and selectivity. In addition, the catalyst composition is also inexpensive in terms of the metal used to modify the zeolite.

In the context of the present invention, the zeolite included in the catalyst composition is understood to mean aluminosilicate, aluminophosphate (AIPO) or silicoaluminophosphate (SAPO). Such inorganic porous materials are known to those skilled in the art. An overview of these features is given in Kirk-Othmer Encyclopedia of Chemical Technology, Volume 16, p 811-853; in Atlas of Zeolite Framework Types, 5th edition, (Elsevier, 2001)] and in the patent publications cited above. The zeolite of the catalyst composition according to the invention is a crystalline material having a uniform pore size and channel-like framework structure, the pore or channel being characterized by a 10-ring structure. Such zeolites are called mesoporous size zeolites and have a pore dimension in the range of 5 to 7 GPa. Like beta zeolites, 12-ring structured zeolites are called large pore size zeolites, and 8-ring structured zeolites are called small pore size zeolites. The above mentioned Atlas of Zeolite Framework Types lists various zeolites based on their ring structure.

The zeolite is preferably in the so-called hydrogen form, which means that the sodium or potassium content is very low, preferably 0.1, 0.05, 0.02 or 0.01 mass% or less, more preferably the presence of sodium is below the detection limit.

The zeolite in the catalyst composition according to the invention is preferably aluminosilicate. Before being modified by the particular metal of the present invention, any aluminosilicate that is active in converting aliphatic oxygenates to aromatics can be applied. Aluminosilicate zeolites may be characterized by the Si / Al ratio of the framework. This ratio can vary widely from catalyst composition according to the invention. Preferably the Si / Al ratio is about 5 to 1000, more preferably about 8 to 500 or 10 to 300. Examples of suitable materials include ZSM series, or mixtures thereof. Preferred materials are known as ZSM-5, ZSM-11, ZSM-23, ZSM-48 and ZSM-57.

In addition, aluminophosphates of medium pore size may be used as zeolites, such as AIPO-11 or AIPO-41.

In another preferred embodiment, the zeolite of the catalyst composition used in the process of the invention is silicoaluminophosphate (SAPO). SAPO materials retain the properties of both aluminosilicates and aluminophosphates. Any SAPO of medium pore size that is active in converting aliphatic oxygenates to aromatics before being modified by the particular metals of the present invention can be applied.

The catalyst composition according to the invention consists essentially of certain zeolites containing from 0.0001 to 20% by weight of lanthanum (La), based on the total catalyst composition. Any minimum amount of lanthanum is required to improve the selectivity of the catalyst to form aromatics from aliphatic oxygenates. That is, the catalyst preferably contains at least 0.001, 0.005, 0.01, 0.05, 0.1, 0.2, 0.5 or even 1 mass% of La. If the zeolite contains an excessively high content of metal, the pores of the zeolite may be at least partially blocked, resulting in a shielding effect. Thus, the La content of the catalyst is preferably at most 15, 10, 8, 6, 5 or even at most 4 mass%.

The catalyst composition according to the present invention is based on the total catalyst composition, 0.0001 to 20% by mass of lanthanum (La) and at least one M element selected from the group consisting of molybdenum (Mo), cerium (Ce) and cesium (Cs) 0.0001 Consisting essentially of certain zeolites containing from 20% by mass. The presence of one or more of these elements has been found to increase the production of aromatics from aliphatic oxygenates. Thus, the catalyst contains at least 0.001, 0.005, 0.01, 0.05, 0.1, 0.2, 0.5 or even at least 1% by mass of the above elements, but preferably contains at most 15, 10, 8, 6 or 5% by mass.

The La-M / zeolite catalyst composition according to the present invention preferably contains at least two elements selected from the group consisting of Mo, Ce and Cs in order to further improve the performance in the conversion of methanol to aromatics and the like.

In a more preferred embodiment, the La-M / zeolite catalyst composition according to the present invention further contains copper (Cu) and / or zinc (Zn) as additional element (s) in addition to element M as defined herein; Both elements may be present in an amount equal to the amounts given for La and at least one M above. Such preferred catalysts according to the present invention include La-Mo-Zn / zeolites and La-Mo-Cu-Zn / zeolites.

The total metal content of the La-M / zeolite composition according to the invention is preferably in the range from 0.1 to 25% by mass, or from 0.2 to 20% by mass.

The various metal elements contained in the catalyst according to the invention are present in the zeolite structure as framework elements or as extra-framework elements; Present as a counterion in the zeolite; Or on the surface, such as in the form of a metal oxide; Or a combination of these forms.

The catalyst composition La-M / zeolite according to the invention described above may optionally contain components which do not negatively affect the binder, ie the catalyst performance, but which serve primarily to provide physical integrity and mechanical strength to the catalyst particles. The binder may contain primarily a support or filler to dilute the catalytic activity; The binder material may also act as a glue to hold the components together; The two functions can also be combined in one material. Such binders are known to those skilled in the art. Examples of suitable materials include clays such as alumina, silica, kaolin, or composites thereof. If used, the binder is preferably silica.

Catalyst compositions according to the invention can be prepared using methods suitable for the preparation and modification of zeolites as known to those skilled in the art; Examples include impregnation, calcination, steam and / or other heat treatment steps.

If the catalyst composition must contain a binder in addition to the modified zeolite, such a composition can be obtained, for example, by mixing the modified zeolite and the binder in a liquid and molding the mixture by applying methods known to those skilled in the art in the form of pellets or tablets. .

The invention also relates to the use of the catalyst composition according to the invention as a catalyst in the preparation of aromatic hydrocarbons from various chemical reactions, such as aliphatic hydrocarbons and / or oxygenated hydrocarbons.

The invention furthermore relates to a process for converting a feed stream containing an oxygenated C 1 -C 10 aliphatic hydrocarbon compound to a product stream containing an aromatic hydrocarbon, wherein the feed is contacted with a catalyst composition according to the invention. It relates to a method comprising a step.

In the process according to the invention, any hydrocarbon feedstock containing oxygenated lower aliphatic hydrocarbon compounds can be used as feed stream. Oxygenated hydrocarbon compounds herein include aliphatic moieties and at least one oxygen atom, such as an alcohol; ether; It is defined to include hydrocarbons containing carbonyl compounds such as aldehydes, ketones, carboxylic acids.

The oxygenated hydrocarbon compound preferably contains 1 to about 4 carbon atoms. Suitable oxygenated hydrocarbons include straight or branched chain alcohols, and unsaturated analogs thereof. Examples of such compounds include methanol, ethanol, isopropanol, n-propanol, dimethyl ether, diethyl ether, methyl ethyl ether, formaldehyde, dimethyl ketone, acetic acid and mixtures thereof.

The feed stream of the process according to the invention preferably comprises C1-C4 alcohols and / or derivatives thereof, more preferably methanol and / or derivatives thereof, such as a methanol / dimethyl ether mixture.

The feed stream may further contain one or more diluents, the concentration of which may vary within various ranges; It is preferred to range from about 10 to 90 vol% of the feed. Examples of suitable diluents include helium, nitrogen, carbon dioxide and water.

In addition, the feed stream may contain other non-aromatic hydrocarbons such as paraffins and / or olefins; In particular, they may contain C1-C5 hydrocarbons. In a preferred manner of carrying out the process according to the invention, the feed stream contains aliphatic hydrocarbons which are recycled from the product stream, for example after removal of aromatic components, for example after mixing with an oxygenate containing stream and contacting the catalyst composition. An advantage of this is that higher conversions to aromatics are obtained because the catalysts of the present invention are also active in converting paraffins and olefins to aromatics.

Contacting the catalyst composition with the feed stream can be carried out in any suitable reactor as known to those skilled in the art, such as a fixed bed, a fluidized bed or any other circulating bed or moving bed reactor.

The contacting step may be performed at a temperature range of about 250 to 750 ° C. Higher temperatures generally improve conversion to aromatics, with temperatures preferably at least about 300, 350 or 400 ° C. Since higher temperatures can induce side reactions or promote deactivation of the catalyst, the temperature is preferably at most about 700, 600 or 550 ° C. It is preferable that reaction temperature is between 400-550 degreeC.

Suitable pressures for carrying out the contacting step range from about atmospheric pressure to 3 MPa and the pressure is preferably about 2.5, 2.0, 1.5, 1.0 or less, or even 0.5 MPa or less.

The flow rate at which the feed stream is fed to the reactor can vary, but the weight space velocity (WHSV) is in the range of about 0.1 to 500 h ⁻¹ , more preferably in the range of about 0.5 to 250 h ⁻¹ or 1 to 100 h ⁻¹ It is preferable that it is a range. WHSV is the ratio of the rate (weight per hour or mass) at which the feed stream is fed to the reactor divided by the weight of the catalyst composition in the reactor and is therefore the reciprocal of the contact time.

The product stream in the process according to the invention comprises in addition to aromatic hydrocarbons saturated and unsaturated aliphatic hydrocarbons, and optionally unconverted oxygenates.

In a preferred process of advancing the process according to the invention, the yield of the aromatics is fed to the subsequent second reaction stage to bring the reaction mixture into contact with the further catalyst composition, for example aliphatic hydrocarbons, especially those present in the product stream. It is further increased due to the increase in the content of aromatics by catalytic conversion of olefins. Suitable further catalysts include the catalyst compositions of the present invention, and any of the aromatization catalysts mentioned in the prior art.

The invention will now be illustrated by the experiments described below.

Comparative Experiment A

Aluminosilicate ZSM-5 (from Geolists) was calcined at 550 ° C. Catalyst particles of 40 to 60 mesh size were loaded into a tubular fixed bed reactor for methanol conversion. The reaction was carried out at a weight space velocity of 9 h ⁻¹ (WHSV) for the methanol feed under a temperature of 450 ° C., pressure of 1 atmosphere. Product stream compositions were analyzed by standard GC techniques. The results are summarized in Table 1.

Catalytic activity is measured by the amount of liquid organic compound formed per hour, ie the amount of liquid organic is a measure of the amount of aromatic compound formed. In addition, in Table 1, TMB means trimethylbenzene; ΣBTX is defined as the total BTX mass% in the product divided by the methanol conversion (mass%) and multiplied by 100; Σ xylene is a value obtained by dividing the mass% of total xylenes (m, p, o) in the product by the methanol conversion rate (mass%) and multiplying by 100.

Comparative Experiment B

ZSM-5 (65%) and alumina Al ₂ O ₃ (35%) were mixed in water and impregnated with the 1.1% Re ₂ O ₃ mixture, dried overnight at 120 ° C. and then calcined at 550 ° C. Catalysts of 40 to 60 mesh size were loaded into a tubular fixed bed reactor for methanol conversion. The reaction was carried out at a weight space velocity of 9 h ⁻¹ (WHSV) for the methanol feed under a temperature of 450 ° C., pressure of 1 atmosphere. The test progress results are summarized in Table 1.

Comparative Experiment C

The catalyst was prepared by ion exchange and heat treatment of commercially available ZSM-5 aluminosilicates (Zeolists) using the desired amount of metal and the following known procedures. 0.6 g of lanthanum nitrate (Fluka) was dissolved in 100 g of distilled water and heated to 60 to 65 ° C under continuous stirring. 10 g of ZSM-5 was added to the lanthanum nitrate solution and heated to 85 ° C. for 8 hours in an airtight container (about 2 mass% of lanthanum was added to ZSM-5); This material was then filtered and washed with 2 liters of hot water. The resulting catalyst slurry was dried for 16 h in a 120 ° C. closed oven. The dried material was then calcined at 450 ° C. in 1 ° C. per minute and maintained at this temperature for 6 hrs.

Catalysts with a particle size of 40 to 60 mesh were loaded into a tubular fixed bed reactor for methanol conversion. The reaction was carried out at a weight space velocity of 9 h ⁻¹ (WHSV) for the methanol feed under a temperature of 450 ° C., pressure of 1 atmosphere. The results are summarized in Table 1.

Comparative Experiment D

The catalyst was prepared as in Comparative Experiment C, but 5 g of lanthanum nitrate was dissolved in 100 g of distilled water, and about 16 mass% of La was added to ZSM-5.

The methanol conversion reaction was performed as in Comparative Experiment C, and the results are shown in Table 1.

Comparative Experiment E

Similar to Comparative Experiment C, La-modified catalysts were prepared from commercial beta zeolites (Zeolists).

A dried and calcined catalyst of 40 to 60 mesh size containing about 2% by mass of La was used for methanol conversion, similar to comparative experiment C. The results are summarized in Table 1.

Comparative Experiment F

Gallium containing zeolite catalysts were prepared by first calcining ZSM-5 (Zeolists) at 538 ° C. according to the procedure of US 4822939. Then 4 g of calcined ZSM-5, 8 g of gallium nitrate in hydrated form, and 60 g of water were placed in a Teflon bottle and heated to 150 ° C. for 18 hours. The product obtained was washed, changed to ammonium form and calcined in air.

Catalysts of 40 to 60 mesh size were loaded into a tubular fixed bed reactor for methanol conversion. The reaction was performed as in Comparative Experiment C, and the results are summarized in Table 1.

Example  One

Similar to Comparative Experiment C, a modified ZMS-5 catalyst was prepared by dissolving 0.6 g of lanthanum nitrate in 100 g of distilled water, 0.5 g of molybdenum oxide, 0.06 g of zinc oxide, and 2.6 g of copper nitrate trihydrate in 100 g of 85 ° C water. . The two solutions were mixed and 10 g of ZSM-5 was added to the solution, which was then heated in an airtight container at 85 ° C. for 8 hours, resulting in about 2% by mass La, 3% by mass Mo, 0.5% by mass Zn and 7% by mass. Cu is added to ZSM-5.

Similar to comparative experiments C and D, dried and calcined catalysts were used for methanol conversion. Table 1 shows the marked improvement in productivity and BTX selectivity.

Example  2

A commercial ZSM-5 product from Zeolite was prepared by ion exchange and heat treatment with the desired amount of metal. 0.6 g of lanthanum nitrate (Fluka) was dissolved in 100 g of distilled water and heated at 60 to 65 ° C under continuous stirring. 0.5 g of molybdenum oxide and 0.06 g of zinc oxide were dissolved in 100 g of 85 ° C water at pH 5. The two solutions were combined and 10 g of ZSM-5 was added to the solution and heated to 85 ° C. for 8 hours in a closed vessel. This represents the addition of about La (2%), Mo (3%) and Zn (0.5%) to ZSM-5. The resulting catalyst was filtered off and washed with 3 L of hot water. The resulting catalyst slurry was dried for 16 h in a 120 ° C. closed oven. The dried catalyst was calcined in a rotary furnace increasing by 1 ° C. per minute up to 450 ° C. and held at 450 ° C. for 6hr.

Catalysts of 40 to 60 mesh size were loaded into a tubular fixed bed reactor for methanol conversion. The reaction was carried out at a weight space velocity of 9 (WHSV) for the methanol feed under a temperature of 450 ° C. and a pressure of 1 atmosphere. Test progress results are shown in Table 1.

Example  3

Similar to Comparative Experiment C, the catalyst was prepared by ion exchange and heat treatment of ZSM-5 (Zeolists) with 0.6 g of lanthanum nitrate dissolved in 100 g of distilled water and 0.5 g of molybdenum oxide dissolved in 100 g of water; As a result, about 2 mass% of La and 3 mass% of Mo existed in ZSM-5. Dry and calcined catalysts of 40 to 60 mesh size were used for methanol conversion similar to comparative experiment C. The results are summarized in Table 1.

Example  4

Similar to Comparative Experiment C, the catalyst was prepared by ion exchange and heat treatment of ZSM-5 (Zeolists) with 0.6 g of lanthanum nitrate dissolved in 100 g of distilled water and 0.7 g of cesium nitrate dissolved in 100 g of water; As a result, about 2 mass% of La and 4.5 mass% of Cs existed in ZSM-5. Dry and calcined catalysts of 40 to 60 mesh size were used for methanol conversion similar to comparative experiment C. Table 1 shows the marked improvement in productivity and BTX selectivity.

Comparative Experiment G

Comparative experiment C was repeated, but in this experiment a mixed feed consisting of methanol / ethylene / propylene / N 2 (36: 7.7: 6.3: 50) was reacted on the catalyst at 450 ° C., 1 atm under a total flow of 65 cc / min. The results are shown in Table 2.

Comparative experiment H

Comparative experiment F was repeated, but in this experiment the feed consisting of a methanol / ethylene / propylene / N2 mixture (36: 7.7: 6.3: 50) was reacted on the catalyst at 450 ° C., 1 atm under a total flow of 65 cc / min. The results are shown in Table 2.

Example  5

Example 2 was repeated, but in this experiment a feed consisting of a methanol / ethylene / propylene / N2 mixture (36: 7.7: 6.3: 50) was reacted on the catalyst at 450 ° C., 1 atm under a total flow of 65 cc / min. The results are presented in Table 2 and show a marked improvement in productivity and aromatide selectivity over La modified zeolites and Ga modified zeolites (Comparative Experiments G and H).

TABLE 1

TABLE 2

Claims (12)

0.0001 to 20 mass% of La (lanthanum); 0.0001 to 20 mass% of at least one M element selected from the group consisting of molybdenum (Mo), cerium (Ce), and cesium (Cs); 10 ring structured zeolites; And optionally a catalyst composition La-M / zeolite, consisting essentially of binder (mass% based on total catalyst composition). The catalyst composition of claim 1, wherein the zeolite is crystalline aluminosilicate. The catalyst composition of claim 2, wherein the aluminosilicate is selected from the group consisting of ZSM-5, ZSM-11, ZSM-23, ZSM-48, and ZSM-57. The catalyst composition according to any one of claims 1 to 3, which contains 0.01 to 10% by mass of La. The catalyst composition according to any one of claims 1 to 4, which contains 0.01 to 10% by mass of at least one M element selected from the group consisting of Mo, Ce or Cs. The catalyst composition according to any one of claims 1 to 5, which contains at least two elements selected from the group consisting of Mo, Ce and Cs. The catalyst composition according to any one of claims 1 to 6, which further contains copper (Cu) and / or zinc (Zn). A process for converting a feed stream containing an oxygenated C 1 -C 10 aliphatic hydrocarbon compound to a product stream containing an aromatic hydrocarbon, the method comprising contacting the feed with the catalyst composition of any one of claims 1-7. Method comprising the steps. The method of claim 8, wherein the feed stream comprises C 1 -C 4 alcohols and / or derivatives thereof. The method of claim 8, wherein the feed stream comprises methanol and / or derivatives thereof. The process of claim 8, wherein the feed stream further comprises C 1 -C 5 hydrocarbons. The method according to claim 8, wherein the temperature is in the range of 250 to 750 ° C., the pressure is in the range of atmospheric pressure to 3 MPa, and the WHSV is in the range of 0.1 to 500 h ⁻¹ .